Co-axial sway bar for a suspension system

ABSTRACT

A suspension system for a heavy duty truck or trailer is disclosed as having a frame and including a first swing arm having a first elongated portion and a first mounting member having a central axis and coupled to the first elongated portion. The suspension assembly also includes a second swing arm including a second elongated portion and a second mounting member having a central axis and coupled to the second elongated portion. The second mounting member is coaxially aligned with the first mounting member to define an axis of rotation for the first swing arm and the second swing arm. The suspension assembly finally includes a connecter coupled to at least one of the first mounting member and the second mounting member and a sway bar having a central axis, wherein the sway bar is coupled to the first swing arm and the second swing arm and positioned such that the central axis of the sway bar is coaxially aligned with the axis of rotation for the first swing arm and the second swing arm.

BACKGROUND

The present application generally relates to suspension systems.Specifically, the present application relates to a sway bar that may beused on a trailing arm suspension. Such a sway bar may be located alongan axis of rotation for the trailing arms of such a suspension.

A suspension system is used to couple the chassis of a vehicle to aground surface. Vehicles traveling along a surface (e.g., pavement,asphalt, gravel, earth, sand, etc.) may encounter various drivingconditions. A first driving situation is where the vehicle travels overan obstacles or variations. Such obstacles may include rocks, potholes,and curbs, among obstructions, and such variations may includedepressions, inclines, and bumps, among other deviations from thesurface. Further, a vehicle may encounter a second driving situationwhere the vehicle is steered aggressively. A vehicle may encounter athird driving situation where the vehicle is steered around a cornerhaving a large radius (i.e., a long and sweeping driving maneuver).Still other driving situations are possible and vary based on thesurfaces, speeds, and environment involved.

Suspension systems are designed to at least partially isolate the bodyof a vehicle during such driving situations. Traditional suspensionsystems include the MacPherson strut system, the “double A-arm”suspension system, and the trailing arm suspension system, among others.A trailing arm suspension system includes two swing arms that rotateabout a pivot axis. Such systems may further include springs, struts,and a sway bar, among other components. A sway bar may be included tocouple the opposing sides of a suspension system to encourage movementof one side upon movement of the other. As one side of the suspensionreceives an input force, the force may be transmitted to the other sideby twisting the sway bar. Such twisting and transfer is oftenaccomplished by offsetting the sway bar from the pivot axis usingvarious linkages. Traditional designs often mount the sway barexternally from the suspension system (e.g., on the top of the shocktower) or through other suspension components. Such a sway bar positionrequires engineers to vary the design of other suspension components,the frame, and the support structure to accommodate the sway bar.Further, sway bars often impact other suspension or chassis componentsduring jounce or rebound, and such impact may limit the potential wheeltravel of the suspension system.

Loading and unloading from inputs through the suspension over the lifeof the sway bar makes sway bars particularly vulnerable to mechanicalfailure. The surface finish and condition of sway bars impacts thelikelihood the sway bar will fail during a period of time. Protecting asway bar from surface imperfections caused by impacting a surface (e.g.,interacting with a curb surface, etc.) or an obstacle (e.g., striking arock, impacts from road debris, etc.) may improve the life of the swaybar and prevent premature failure. However, traditional sway bar designsoften leave the sway bar exposed to road debris and obstacles.Accordingly, a need exists for a suspension system having a sway barthat is protected from road debris and allows for greater wheel travel.

SUMMARY

One embodiment of the application relates to a suspension system for aheavy duty truck or trailer having a frame and including a first swingarm having a first elongated portion and a first mounting member havinga central axis and coupled to the first elongated portion. Thesuspension assembly also includes a second swing arm including a secondelongated portion and a second mounting member having a central axis andcoupled to the second elongated portion. The second mounting member iscoaxially aligned with the first mounting member to define an axis ofrotation for the first swing arm and the second swing arm. Thesuspension assembly finally includes a connecter coupled to at least oneof the first mounting member and the second mounting member and a swaybar having a central axis, wherein the sway bar is coupled to the firstswing arm and the second swing arm and positioned such that the centralaxis of the sway bar is coaxially aligned with the axis of rotation forthe first swing arm and the second swing arm.

Another embodiment of the application relates to a suspension system fora vehicle having a frame. The suspension system includes a firstinterface member and a second interface member positioned along a commoncentral axis, a first and a second body member coupled to the firstinterface member and the second interface member and configured torotate about the common central axis, and a torsion spring coupled tothe first interface member and the second interface member and disposedalong the common central axis.

Yet another embodiment of the application relates to an axle assemblyfor a heavy duty truck. The axle assembly includes a first wheel hub anda second wheel hub, a first drive axle coupled to the first wheel huband a second drive axle coupled to the second wheel hub and adifferential assembly coupled to the first drive axle and the seconddrive axle. The axle assembly also includes a first swing arm includinga first elongated portion and a first mounting member having a centralaxis and coupled to an end of the first elongated portion, a secondswing arm including a second elongated portion and a second mountingmember having a central axis and coupled to the second elongatedportion. The second mounting member is coaxially aligned with the firstmounting member to define an axis of rotation for the first swing armand the second swing arm and the first wheel hub is coupled to an end ofthe first elongated portion and the second wheel hub is coupled to anend of the second elongated portion. The axle assembly finally includesa connecter configured to receive at least one of the first mountingmember and the second mounting member and a sway bar having a centralaxis. The sway bar is coupled to the first swing arm and second swingarm and positioned such that the central axis of the sway bar iscoaxially aligned with the axis of rotation.

Alternative exemplary embodiments relate to other features andcombinations of features as may be generally recited in the claims.

BRIEF DESCRIPTION OF THE FIGURES

The disclosure will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingfigures, in which:

FIG. 1 is an elevation view of a suspension system on a non-driving axlehaving a coaxial sway bar.

FIG. 2 is an elevation view of a suspension system on a driving axlehaving a coaxial sway bar.

FIG. 3 is a cross sectional view of a suspension system having a coaxialsway bar.

FIG. 4 is a cross sectional view of a suspension system having a coaxialsway bar.

FIG. 5 is an elevation view of one joint within a suspension systemhaving a coaxial sway bar.

FIG. 6 is an elevation view of one joint assembly within a suspensionsystem having a coaxial sway bar.

FIG. 7 is a cross sectional view of one joint assembly within asuspension system having a coaxial sway bar.

FIG. 8 is a schematic view of a suspension system on a non-driving axlehaving a coaxial sway bar.

FIG. 9 is a schematic view of a suspension system on a non-driving axlehaving a coaxial sway bar.

FIG. 10 is a cross sectional view of a coupling for a coaxial sway bar.

DETAILED DESCRIPTION

Before turning to the figures, which illustrate the exemplaryembodiments in detail, it should be understood that the presentapplication is not limited to the details or methodology set forth inthe description or illustrated in the figures. It should also beunderstood that the terminology is for the purpose of description onlyand should not be regarded as limiting.

Referring to the exemplary embodiment shown in FIG. 1, a vehicle mayinclude a non-driven axle, shown as suspension assembly 10. Such avehicle may be an off road truck, a heavy duty truck, a trailer, orother known vehicle designs. Suspension assembly 10 is intended to aidin isolating a vehicle body from forces imparted on the vehicle from aroad surface, an obstacle, or another input (e.g., explosion, etc.).Such isolation may include absorbing forces imparted on suspensionassembly 10 or may include directing forces within suspension assembly10 to modify the reaction experienced by the vehicle body. As shown inFIG. 1, suspension assembly 10 includes a first member, shown as firstswing arm 20 and a second member, shown as second swing arm 30. Firstswing arm 20 and second swing arm 30 may be arranged on opposing sidesof a vehicle chassis (not shown). According to the exemplary embodimentshown in FIG. 1, first swing arm 20 and second swing arm 30 extendrearward and pivot about an axis, shown as pivot axis 35.

Referring still to the exemplary embodiment shown in FIG. 1, suspensionassembly 10 further includes a wheel end, shown as hub 40 coupled to anend of first swing arm 20. Hub 40 is configured to rotate about acenterline and interface with a driven member (e.g., tire, etc.) thatcouples suspension assembly 10 to a road surface. According to anexemplary embodiment, hub 40 includes various internal components (e.g.,bearings, bushings, washers, brake assemblies, etc.) to facilitate theoperation of a vehicle or suspension assembly 10.

As shown in FIG. 1, suspension assembly 10 may further include a spring,shown as air bag 50 that supports the sprung mass of the vehicle.According to the exemplary embodiment shown in FIG. 1, air bag 50 has afirst end coupled to first swing arm 20 and a second end configured tobe coupled to a vehicle chassis. According to various alternativeembodiments, air bag 50 may be coupled to another portion of first swingarm 20, suspension assembly 10 may include a plurality springs, such asair bags 50, or suspension assembly 10 may not include a spring, such asair bag 50. Air bag 50 absorbs energy and prevents the vehicle body fromexperiencing a portion of an input force. Such absorption may occur byallowing for relative movement between the first and second ends of airbag 50. A relative movement between the first and second ends of allowsair bag 50 to utilize the energy associated with the input force tocompress air within a chamber. According to an alternative embodiment,air bag 50 may comprise a spring or another resilient member thatcompresses to absorb energy, thereby limiting the amount of energytransferred to the vehicle body.

According to an exemplary embodiment, suspension assembly 10 furtherincludes a damper, shown as strut 60. As shown in FIG. 1, strut 60 has afirst end coupled to first swing arm 20 and a second end configured tobe coupled to a vehicle chassis. Strut 60 may include internalcomponents that manipulate the response forces generated from an inputforce. By way of example, such internal components may include a housingcoupled to the second end and containing a fluid. The fluid interactswith a plurality of openings within a piston coupled to the first end.As strut 60 receives an input force, the output force imparted on thevehicle chassis is affected by the movement of the piston though thefluid. As shown in FIG. 1, strut 60 may be angled with respect to airbag 50. According to an alternative embodiment, strut 60 may be arrangedcoaxially with air bag 50 (e.g., configured as a coil-over design).Suspension assembly 10 may include a single strut 60, a plurality ofstruts 60, or may not include a strut 60.

As shown in FIG. 1, suspension assembly 10 may include a sway bar (e.g.,anti-sway bar, torsion spring, roll stability device, etc), shown assway bar 70. Sway bar 70 may be shaped in various configurations as astraight member, a member having a curved shape, a member having aplurality of bends, or a member including an assembly of subcomponents.As shown in FIG. 1, sway bar 70 has a circular cross section. Accordingto various alternative embodiments, sway bar 70 may have a square orhexagonal cross section, may comprise a tubular structure, may have across section that varies along a length of sway bar 70, or may becomprised of various subcomponents.

While sway bar 70 is shown for clarity in FIG. 1 as partially exposed,suspension assembly 10 may further include a cover (e.g., guard, plate,tube, etc.) configured to protect sway bar 70 from damage by impactsthat may occur with debris or obstacles. Protecting sway bar 70 mayextend the useable life of sway bar 70 by preventing crack formation orpropagation that may lead to fatigue failure. Such a cover may be atubular structure coupled to first swing arm 20 and second swing arm 30.According to an alternative embodiment, the cover may comprise a bootslidably coupled to sway bar 70. According to still another alternativeembodiment, the cover may include a shield coupled to first swing arm20, second swing arm 30, or another component of suspension assembly 10.

According to the exemplary embodiment shown in FIG. 1, sway bar 70 ispositioned along the length of pivot axis 35 and at least partiallywithin first swing arm 20 and second swing arm 30. Locating sway bar 70along pivot axis 35 may provide the advantage of further protecting swaybar 70 from damage by impacts that may occur with debris or obstacles.Locating sway bar 70 along pivot axis 35 may provide the furtheradvantage of improving the wheel travel of suspension assembly 10because sway bar 70 may not interfere with other components ofsuspension assembly 10.

According to the exemplary embodiment shown in FIG. 1, suspensionassembly 10 includes a first coupler (e.g., connector, pivot, etc.),shown as first joint 100, a second coupler (e.g., connector, pivot,etc.), shown as second joint 200, a third coupler (e.g., connector,pivot, etc.), shown as third joint 210, and a fourth coupler (e.g.,connector, pivot, etc.), shown as fourth joint 220. As shown in FIG. 1,first joint 100 and second joint 200 may be coupled to an end of firstswing arm 20 and configured to facilitate rotation of first swing arm 20about pivot axis 35. Similarly, third joint 210 and fourth joint 220 maybe coupled to an end of second swing arm 30 and configured to facilitatethe rotation of second swing arm 30 about pivot axis 35.

Referring next to the exemplary embodiment shown in FIG. 2, a vehiclemay include an axle assembly, shown as driven axle 300. Such a vehiclemay include an off road truck, a heavy duty truck, or other knownvehicle designs. Driven axle 300 may isolate a vehicle body from forcesimparted on the vehicle from a road surface, an obstacle, or anotherinput (e.g., explosion, etc.) and also provide a motive force to propelthe vehicle. Further, driven axle 300 may receive an input from apowering device (e.g., motor, engine, etc.) or may further include apowering device coupled a portion of driven axle 300.

As shown in FIG. 2, driven axle 300 includes a first member, shown asfirst swing arm 320 and a second member, shown as second swing arm 330.First swing arm 320 and second swing arm 330 rotate about a common axis,shown pivot axis 335. Such rotation is facilitated by a first coupler,shown as first joint 350, a second coupler, shown as second joint 355, athird coupler, shown as third joint 360, and a fourth coupler, shown asfourth joint 365. According to an exemplary embodiment, joints 350, 355,360, and 365 further couple first swing arm 320 and second swing arm 330to a chassis of a vehicle. As shown in FIG. 2, driven axle 300 furtherincludes a resilient member, shown as strut 380 configured to affect theforces imparted by driven axle 300 on a vehicle body in response to aninput force and a roll stability member, shown as sway bar 395configured to couple the opposing sides of driven axle 300. According toan exemplary embodiment, driven axle 300 further includes a gear train,shown as differential 375 coupled to an end of drive axles, shown ashalf shafts 370. As shown in FIG. 2, an end of half shafts 370 mayinterface with a wheel end, shown as hub 340. Hub 340 may be coupled tofirst swing arm 320 or second swing arm 330 and a driven member, shownas tire 390. According to an exemplary embodiment, such coupling mayallow driven axle 300 to rotate tires 390 in response to a torque inputreceived by differential 375.

Referring next to FIGS. 3-4, a cross section of suspension assembly 10is shown, according to an exemplary embodiment. As shown in FIG. 3, swaybar 70 extends laterally within suspension assembly 10 and includes afirst end 72 and a second end 74. According to an exemplary embodiment,first end 72 of sway bar 70 may be coupled to first swing arm 20 atfirst joint 100, sway bar 70 may extend through second joint 200 andthird joint 210, and second end 74 of sway bar 70 may be coupled tosecond swing arm 30 at fourth joint 220. According to an alternativeembodiment, sway bar 70 is coupled to first swing arm 20 and secondswing arm 30 at second joint 200 and third joint 210, at other pointsalong pivot axis 35, or at other locations on first swing arm 20 andsecond swing arm 30.

Referring still to FIGS. 3-4, sway bar 70 couples the two sides ofsuspension assembly 10. Such coupling may provide various advantagesdepending on the driving conditions encountered. A first drivingcondition occurs as the tire of a vehicle impacts an obstacle orvariation. Such obstacles may include rocks, potholes, and curbs, amongother obstructions, and such variations may include depressions,inclines, and bumps, among other deviations from the surface. A tire maybe coupled to hub 40 along first swing arm 20, and as the tireencounters the obstacle or variation, a force is transmitted through hub40 and into first swing arm 20. Absent sway bar 70, first swing arm 20may rotate about pivot axis 35 independent of second swing arm 30. Suchindependent movement may cause first swing arm 20 to rotate upward andcause the vehicle chassis to roll. By way of example, the vehiclechassis may roll upward and away from first swing arm 20 (i.e. counterclockwise about a length of the vehicle from a front view) as hub 40moves upward or the vehicle chassis may roll downward and towards firstswing arm 20 (i.e. clockwise about a length of the vehicle from a frontview) as hub 40 moves downward.

Referring still to FIGS. 3-4, installing sway bar 70 may impact theperformance of the vehicle during the first driving condition. Asuspension assembly 10 including sway bar 70 may roll less compared to asuspension system having decoupled swing arms. As a tire impacts anobstacle or variation, an input force having a magnitude and directionmay be transmitted through hub 40 and interact with first swing arm 20and the vehicle chassis. The input force creates a turning torque uponsway bar 70 at the points where sway bar 70 is coupled to first swingarm 20, and this turning torque is transmitted to the opposite end ofsway bar 70. Such a turning torque may act to rotate second swing arm 30thereby causing second hub 45 to rotate upward along an arced path.According to an exemplary embodiment, sway bar 70 may comprise aresilient member that twists to absorb a portion of the input energythereby contributing to the spring rate of the suspension. Sway bar 70may also twist to allow for relative movement between the opposing wheelhubs. Such upward movement and torque acting on second swing arm 30 mayimpart a second force upon the vehicle chassis. This second force actsagainst the input force to counteract body roll about a centerline ofthe vehicle thereby reducing the amount of body roll experienced inresponse to a tire impacting an obstacle or variation.

Referring still to FIGS. 3-4, a second and third driving condition mayoccur where the vehicle is steered aggressively or steered around acorner having a large radius. Either of these driving conditions causesa body roll opposite the steering direction (e.g., a turn to the rightcreates body roll to the left, etc.) as the vehicle mass acts about acenter of gravity for the vehicle. A decoupled suspension system withouta sway bar may not be able to correct for such body roll. As discussedabove, a force applied on first swing arm 20 may be transmitted astorque through sway bar 70 thereby creating an opposing force on secondswing arm 30 that resists body roll.

Referring next to FIGS. 5-7, sway bar 70 is shown coupled to first swingarm 20, according to an exemplary embodiment. Such coupling mayfacilitate a reduction in body roll, as discussed above. According to anexemplary embodiment, sway bar 70 may be coupled to first swing arm 20proximate first end 72. According to an alternative embodiment, sway bar70 is coupled to first swing arm 20 at another location along the lengthof sway bar 70. As shown in FIG. 5, sway bar 70 includes an interface,shown as splined end 76 proximate first end 72. Splined end 76 engagesan interface portion, shown as splined receiver 29 that is coupled tofirst swing arm 20. Such engagement may interlock the movement of firstswing arm 20 and sway bar 70. According to an alternative embodiment,sway bar 70 may be coupled to first swing arm 20 using another knownmethod (e.g., welding, a bolted connection, a press fit connection,thermal fit connection, etc.).

According to an exemplary embodiment, splined end 76 that interfaceswith first swing arm 20 may differ from the opposing interface thatcouples second end 74 of sway bar 70 to second swing arm 30. Accordingto an exemplary embodiment, the interface at second end 74 of sway bar70 may also include a splined connection. Splined end 76 may have adifferent diameter or number of teeth, among other differences, than theinterface at the second end 74 of sway bar 70. According to an exemplaryembodiment, such variation may facilitate the manufacture, assembly, andmaintenance of suspension assembly 10.

During the manufacture of first swing arm 20 and second swing arm 30,splined receiver 29 may be coupled (e.g., bolted, welded, pressed into,etc.) to an end of first swing arm 20. According to an exemplaryembodiment, such splined receiver 29 is received into an end of firstswing arm 20 and welded into place. A similar opposing splined portionmay be received into an end of second swing arm 30. Rotationallylocating splined receiver 29 (i.e. orienting splined receiver 29 aboutpivot axis 35 relative to a similar splined portion proximate second end74) may prove difficult for a suspension system where splined end 76 andthe similar splined portion proximate second end 74 have the same numberof teeth. Such a system would require alignment of the teeth of splinedreceiver 29 and a corresponding splined receiver proximate second end 74because misalignment may prevent proper assembly of suspension assembly10.

According to an exemplary embodiment, varying the number of teethbetween splined receiver 29 and a corresponding splined receiverproximate second end 74 facilitates assembly by providing for allowedmisalignment. During assembly, a user may slide sway bar 70 into asplined receiver proximate second end 74 and determine whether the teethof splined end 76 are aligned with the mating recesses within splinedreceiver 29. Where the teeth of splined end 76 are not aligned with therecesses of splined receiver 29, the user may slide sway bar 70partially out and index the splined portion proximate second end 74within the opposing splined receiver and again check for alignment ofthe teeth of splined end 76 and the recesses within splined receiver 29.According to an exemplary embodiment, such indexing allowed by thedifferent number of teeth may allow a user to slide sway bar 70 intosplined receiver 29 and the opposing splined receiver with minimalinterference (e.g. slide in easily, slide in with slight tapping, etc.).According to an exemplary embodiment, a varied number of teeth allowsfor between 0.5 and 3.0 degrees of misalignment between the recesses ofsplined receiver 29 and the recesses within the corresponding receiverproximate second end 74.

According to an alternative embodiment, misalignment between the teethof splined end 76 and the similar splined portion proximate second end74 may be accommodated during the assembly process of suspensionassembly 10. By way of example, a user may assemble suspension assembly10 by sliding second end 74 of sway bar 70 through first joint 100,second joint 200, third joint 210, and fourth joint 220 and into asplined receiver. The user may then check the alignment between theteeth of splined end 76 and the recesses of splined receiver 29. Wherethe teeth and recesses are misaligned, a user may rotate second swingarm 30 until the teeth of splined end 76 are aligned with the recessesof splined receiver 29. By way of example, rotation of second swing arm30 during assembly may be accomplished by lifting the sprung weight ofthe vehicle. Such an assembly process may cause first swing arm 20 to berotationally offset from second swing arm 30. The weight a vehiclepositioned above suspension assembly 10 may force both tires to contactthe ground surface thereby rotationally aligning first swing arm 20 andsecond swing arm 30. Such forced alignment may impart a preload torqueonto sway bar 70 and produce a suspension having a different springrate. According to an exemplary embodiment, a user may adjust thepreload torque either during initial assembly or in the field byoffsetting first swing arm 20 relative to second swing arm 30. Accordingto an exemplary embodiment, the process of adding a preload torque tosway bar 70 may be used to replace or supplement the allowedmisalignment provided by specifying a different number of teeth forsplined end 76 and the similar splined portion proximate second end 74.

According to an exemplary embodiment, splined receiver 29 has adifferent diameter than the opposing interface portion. By way ofexample, the opposing interface portion may have a diameter that issmaller than splined receiver 29. According to an exemplary embodiment,such variance in diameter allows for a user to assemble suspensionassembly 10 by inserting sway bar 70 in from one side of suspensionassembly 10. Due to the smaller diameter, a user may slide second end 74through splined receiver 29 and into the opposing splined receiver. Adifferent diameter also facilitates maintenance because a user mayremove sway bar 70 without disassembling both sides of suspensionassembly 10. By way of example, a user may disassemble the side ofsuspension assembly 10 proximate first swing arm 20 and slide sway bar70 outward without needing to disassemble the side of suspensionassembly 10 proximate second swing arm 30. Such maintenance benefits maybe especially important to reduce maintenance costs or to increasemaintenance efficiency in hostile environments.

Referring again to FIGS. 5-7, first swing arm 20 may further include afirst coupler, shown as first joint end 22, according to an exemplaryembodiment. First joint end 22 may be coupled to first swing arm 20 ormay be integrally formed with first swing arm 20. As shown in FIG. 5,first joint end 22 may include an extended portion, shown as flange 24.According to an exemplary embodiment, flange 24 limits the movement offirst swing arm 20 along pivot axis 35. First joint end 22 furtherincludes a projection, shown as cylinder 28. As shown in FIGS. 5-7,cylinder 28 may be welded to first swing arm 20. According to analternative embodiment, cylinder 28 may be integrally formed with orotherwise fastened to first swing arm 20. Cylinder 28 may have a tubularcross section, a rectangular cross section, or any other suitable shape.As shown in FIG. 5, splined receiver 29 may be coupled to (e.g.,integrally formed, welded, bolted, etc.) cylinder 28, and cylinder 28may be coaxial with splined receiver 29. Flange 24 may include an outersurface, shown as surface 26 extending from cylinder 28.

Referring to FIG. 6, first joint 100 is shown, according to an exemplaryembodiment. As shown in FIG. 6, first joint 100 may include a support,shown as bracket 110. Bracket 110 may couple suspension assembly 10 tothe chassis of a vehicle. Such coupling may occur through the use offasteners, shown as bolts 114. According to various alternativeembodiments, bracket 110 may be coupled to the chassis of a vehicleusing another known fastening connection (e.g., welding, a compositeinterface, etc.). Bracket 110 may include an inner surface, shown asouter race surface 112. Outer race surface 112 may be hardened to resistwear imparted by forces transmitted through first joint 100.

According to the exemplary embodiment shown in FIG. 6, first joint 100further includes an inner rotatable member, shown as bushing 120. Asshown in FIG. 6, bushing 120 may be shaped as a tubular member. Bushing120 may include an outer bearing surface, shown as outer bushing surface121 that is configured to be received by outer race surface 112. Asshown in FIG. 6, bushing 120 may further include an inner bearingsurface, shown as inner bushing surface 122. According to an exemplaryembodiment, inner bushing surface may be configured to receive an outersurface of cylinder 28. Relative movement between outer bushing surface121 and outer race surface 112 and inner bushing surface 122 andcylinder 28 may be facilitated by a lubricant (e.g., oil, a syntheticmaterial, grease, etc.). Such a lubricant may be disposed within achannel, shown as groove 124. As shown in FIG. 6, groove 124 ispositioned circumferentially along outer bushing surface 121. Accordingto an exemplary embodiment, bushing 120 further includes an opening,shown as aperture 123. Aperture 123 may facilitate the flow of thelubricant into the interface of inner bushing surface 122 and cylinder28.

According to the exemplary embodiment shown in FIG. 6, first joint 100further includes a washer bearing, shown as thrust washer 130. As shownin FIG. 6, thrust washer 130 is sandwiched between surface 26 of flange24 and an extended portion of bushing 120, shown as flange 128. Thrustwasher 130 is intended to reduce the axial side loads experienced by thevarious other components of first joint 100 during the operation ofsuspension assembly 10. By way of example, such side loads may occurduring cornering of the vehicle. Thrust washer 130 may comprise variousmaterials and may be designed to wear in advance of surface 26 or flange128. According to an exemplary embodiment, thrust washer 130 may be madeof a polymeric material. According to an alternative embodiment, thrustwasher 130 may be made of a metal (e.g., brass, steel, etc.).

As shown in FIG. 6, first joint 100 may further include a cover, shownas end cap 140. End cap 140 may be made of a variety of known materials(e.g., steel, a polymer, etc.). As shown in FIG. 6, end cap 140 may bepositioned proximate the outside of first joint 100. It should beunderstood that fourth joint 220 may also include a similar end cap 140positioned proximate the outside of fourth joint 220. End cap 140 mayinclude a plurality of apertures and couplers, shown as fasteners 142.As shown in FIG. 6, fasteners 142 may be received by correspondingopenings, shown as apertures 126 within the end of cylinder 28.According to an exemplary embodiment, end cap 140 may prevent debrisfrom entering first joint 100. According to an alternative embodiment,end cap 140 may limit the movement of sway bar 70 along pivot axis 35.

As shown in FIGS. 6-7, outer bushing surface 121 may be rotatablycoupled to outer race surface 112, and inner bushing surface 122 may berotatably coupled to an outer surface of cylinder 28. According to anexemplary embodiment, cylinder 28 may rotate relative to bracket 110 andbushing 120 after first swing arm 20 receives an input from hub 40.According to an alternative embodiment, cylinder 28 may rotate withbushing 120 relative to bracket 110. According to still anotheralternative embodiment, relative movement among cylinder 28, bracket110, and bushing 120 may occur. Such relative movement may befacilitated by a lubricant, as discussed above. As shown in FIG. 7, thelubricant may be contained within first joint 100 with a resilientmember, shown as seal 150. According to an exemplary embodiment, seal150 is positioned (e.g., pressed into, etc.) within bushing 120 andinterfaces with an outer surface of cylinder 28. Seal 150 may alsoprevent debris from entering first joint 100 and interfering with therelative movement between bushing 120 and cylinder 28.

While the preceding discussion identified the various components offirst joint 100, according to an exemplary embodiment, it should beunderstood that second joint 200, third joint 210, and fourth joint 220may comprise similar components. Such similar components may include asupport and an inner rotatable member coupled to correspondingcylinders. However, second joint 200, third joint 210, and fourth joint220 may comprise additional components.

According to an alternative embodiment, first joint 100 may comprise abearing to rotatably couple first swing arm 20 to the chassis of thevehicle. By way of example, such a bearing may include a roller bearinghaving an inner race, an outer race, and a plurality of spheres disposedbetween the inner race and the outer race. Such a system may furtherinclude a thrust washer configured to limit the axial forces experiencedby the roller bearing. According to an alternative embodiment, firstjoint may comprise a tapered roller bearing having a plurality of angledrollers disposed between an inner and an outer race. According to stillother alternative embodiments, first joint 100 may include other knowncouplers that allow for relative movement between first swing arm 20 orsecond swing arm 30 and the chassis of a vehicle.

Referring next to an alternative embodiment shown in FIG. 8, a stiffenerassembly, shown as control arm assembly 400 includes a first member,shown as first swing arm 420. As shown in FIG. 8, control arm assembly400 includes pin, shown as pivot 410 and a plurality of couplers, shownas joints 415. Pivot 410 facilitates rotation of first swing arm 420about an axis, shown as pivot axis 430. Joints 415 rotatably couplesfirst swing arm 420 to the chassis of a vehicle. By way of example,joints 415 may include various known couplers (e.g., roller bearings,tapered roller bearings, bushings, thrust bearings, etc.).

As shown in FIG. 8, first swing arm 420 may be coupled to pivot 410proximate a first end, shown as pivot end 425. According to an exemplaryembodiment, such coupling may occur directly between first swing arm 420and pivot 410 (e.g., with a bushing, bearing, etc. positioned betweenfirst swing arm 420 and pivot 410). According to an alternativeembodiment, first swing arm 420 may be coupled to pivot 410 throughjoints 415. By way of example, such a configuration may involve couplingfirst swing arm 420 to an outer race of joint 415 and coupling an innerrace of joint 415 to pivot 410. The sprung weight (i.e., the weight ofthe body supported by the suspension) may also be coupled to pivot 410with additional couplers.

Referring still to FIG. 8, first swing arm 420 may be coupled to a wheelhub and tire assembly (not shown), according to an exemplary embodiment.As a vehicle travels along a surface, various obstacles or variationsmay result in forces to be transmitted through first swing arm 420 andinto the various additional components of control arm assembly 400. Sucha vehicle may include a second stiffener assembly that may comprise amirror image of first swing arm 420, joints 415 and pivot 410. As shownin FIG. 8, control arm assembly 400 may include a roll stability device,shown as sway bar 440. According to an exemplary embodiment, sway bar440 may be positioned along pivot axis 430. As shown in FIG. 8, sway bar440 may be coupled to first swing arm 420 with a support, shown asmounting arm 450. The interface between sway bar 440 and mounting arm450 and mounting arm 450 and first swing arm 420 may take various forms(e.g., integrally formed, welded, press fit, thermally fit, bolted,splined, etc.). According to an exemplary embodiment, sway bar 440 maycouple the opposing sides of a vehicle in a manner that providesnumerous advantages, such as those discussed above.

Referring next to the alternative embodiment shown in FIG. 9, astiffener assembly, shown as control arm assembly 500, includes a firstmember, shown as first swing arm 520. First swing arm 520 is coupled ata first end to a wheel end, shown as hub 530 that may interface with atire or another known member capable of supporting at least a portion ofa vehicle (e.g., track, etc.). According to an exemplary embodiment,first swing arm 520 is coupled to a vehicle chassis through a pluralityof couplers, shown as joints 540. As shown in FIG. 9, joints 540 maycomprise roller bearings. According to an alternative embodiment, joints540 may comprise bushings. According to various other alternativeembodiments, joints 540 may comprise tapered roller bearings, thrustbearings, or other known couplers capable of allowing rotationalmovement between first swing arm 520 and the vehicle chassis.

As shown in FIG. 9, first swing arm 520 is coupled to in inner race ofjoint 540 through an interfacing member, shown as tube 525. Such aconfiguration allows first swing arm 520 to rotate about a central axis,shown as pivot axis 550 as first swing arm 520 receives input forcesfrom hub 530. According to an exemplary embodiment, joints 540 and tube525 include centerlines disposed along pivot axis 550.

According to the exemplary embodiment shown in FIG. 9, control armassembly 500 may further include a roll stability device, shown as swaybar 560. As shown in FIG. 9, sway bar 560 may be positioned withincontrol arm assembly 500 such that an axis of ration of sway bar 560 maybe coaxial with pivot axis 550. According to an exemplary embodiment,tube 525 may further include a projection, shown as flange 526. Flange526 may be integrally formed with tube 525 or may be coupled with tube525 (e.g. welded, press fit, etc.). As shown in FIG. 9, control armassembly 500 may further include a cover, shown as end cap 570 coupledto flange 526 with fasteners, shown as bolts 575. While FIG. 9 showssway bar 560 extending past the entire length of first swing arm 520, itshould be understood that sway bar 560 may be coupled to first swing arm520 at any location across first swing arm 520, at a location outside(i.e. further from a centerline of the vehicle) of joints 540, or at alocation inside (i.e. closer to a centerline of the vehicle) of joints540, among other configurations.

As shown in FIG. 9, sway bar 560 includes an interfacing portion, showedas spline 565, proximate a first end of sway bar 560. According to anexemplary embodiment, end cap 570 includes a corresponding splinedportion disposed within a hollow projection, shown as protrusion 573that is configured to receive spline 565. A vehicle may include a secondcontrol arm, joints, and end cap coupled to a second end of sway bar560. By way of example, the second control arm, joints, and end cap maybe arranged in a configuration that mirrors that of control arm assembly500. According to an exemplary embodiment, first swing arm 520experiences a force proximate hub 530 and impart a turning torque ontube 525 and flange 526. Such a turning torque may be transmittedthrough bolts 575 and spline 565 and into sway bar 560, which maytransmit that turning torque to the opposing side of the vehicle.According to an exemplary embodiment, sway bar 560 may couple theopposing sides of a vehicle in a manner that provides numerousadvantages, such as those discussed above with respect to sway bar 70.

Referring next to the alternative embodiment shown in FIG. 10, aninterfacing portion, shown as coupling 600 includes an outer support,shown as tube 610 and a roll stability device, shown as sway bar 620.According to an exemplary embodiment, tube 610 is coupled to a swing armand a vehicle chassis according to the various methods discussed above.As shown in FIG. 10, coupling 600 further includes an interface, shownas ring 630. Ring 630 may be made from various known materials and maybe configured to rotatably couple sway bar 620 with tube 610. Suchcoupling may occur though a first interface between tube 610 and ring630, shown as first splined connection 615 and a second interfacebetween sway bar 620 and ring 630, shown as second splined connection625. According to an alternative embodiment, tube 610 and sway bar 620may be coupled to ring 630 with another known method (e.g., press fit,thermally fit, a keyed connection, etc.).

As shown in FIG. 10, coupling 600 further includes a stopping plate,shown as limiter 640. According to an exemplary embodiment, limiter 640prevents ring 630 from sliding within tube 610. According to anotherembodiment, coupling 600 may not include limiter 640. As shown in FIG.10, limiter 640 further includes a washer, shown as seal 645 that isconfigured to prevent debris from contacting ring 630 or sway bar 620.According to the exemplary embodiment shown in FIG. 10, coupling 600further includes a fastener, shown as snap ring 650 to secure limiter640 within tube 610. According to an alternative embodiment, coupling600 may not include a fastener, and limiter 640 may be otherwise securedwithin tube 610 (e.g., with a threaded connection, etc.).

Referring still to FIG. 10, coupling 600 further comprises a cover,shown as end cap 660. End cap 660 may prevent debris from entering theend of tube 610. As shown in FIG. 10, end cap 660 includes a resilientmember, shown as seal 662 disposed between a portion of end cap 660 andtube 610. End cap 660 may be coupled to tube 610 according with anysuitable means. As shown in FIG. 10, end cap 660 is coupled to tube 610with a threaded connection, shown as threaded interface 664. Such acombination of elements may allow coupler 600 to interlock the rotationof a swing arm and sway bar 620 to allow sway bar 620 to transmitimparted torque to the opposite side of the vehicle thereby providingthe various advantages discussed above. Such a configuration allowsfirst swing arm 20 to rotate about a centerline of sway bar 70 becausethe axis of rotation of sway bar 70 is positioned coaxially with a pivotaxis of the swing arm.

The construction and arrangements of the suspension assembly, as shownin the various exemplary embodiments, are illustrative only. Althoughonly a few embodiments have been described in detail in this disclosure,many modifications are possible (e.g., variations in sizes, dimensions,structures, shapes and proportion of the various elements, values ofparameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter described herein. Someelements shown as integrally formed may be constructed of multipleconnectors or elements, the position of elements may be reversed orotherwise varied, and the nature or number of discrete elements orpositions may be altered or varied. The order or sequence of anyprocess, logical algorithm, or method steps may be varied orre-sequenced according to alternative embodiments. Other substitutions,modifications, changes and omissions may also be made in the design,operating conditions and arrangement of the various exemplaryembodiments without departing from the scope of the present application.

1. A suspension system for a heavy duty truck or trailer having a frame,comprising: a first swing arm including a first elongated portion and afirst mounting member having a central axis and coupled to the firstelongated portion; a second swing arm including a second elongatedportion and a second mounting member having a central axis and coupledto the second elongated portion, wherein the second mounting member iscoaxially aligned with the first mounting member to define an axis ofrotation for the first swing arm and the second swing arm; a connectercoupled to at least one of the first mounting member and the secondmounting member; and a sway bar having a central axis, wherein the swaybar is coupled to the first swing arm with a first splined connectionand coupled to the second swing arm with a second splined connectiondifferent than the first splined connection, wherein the sway bar ispositioned such that the central axis of the sway bar is coaxiallyaligned with the axis of rotation for the first swing arm and the secondswing arm.
 2. The suspension system of claim 1, wherein the first swingarm further comprises a protrusion extending from the first elongatedportion and coupled to the sway bar.
 3. The suspension system of claim1, wherein the sway bar extends through a portion of the first mountingmember.
 4. The suspension system of claim 1, wherein the sway barcomprises an elongated bar coupled to the first mounting member and thesecond mounting member.
 5. The suspension system of claim 4, wherein thesway bar further comprises a first male splined portion proximate afirst end of the elongated bar and the first mounting member furthercomprises a corresponding female splined portion configured to receivethe first male splined portion of the sway bar.
 6. The suspension systemof claim 4, further comprising a cap coupled to the first mountingmember and the sway bar.
 7. The suspension system of claim 6, whereinthe cap is coupled to the first mounting member with a bolted connectionand the cap is coupled to the sway bar with a splined connection.
 8. Thesuspension system of claim 1, wherein the connecter further comprises anouter support member configured to be coupled to the frame of a heavyduty truck or trailer.
 9. The suspension system of claim 8, wherein theconnecter further comprises an inner race coupled to an outer surface ofthe first mounting member and positioned within the outer supportmember.
 10. The suspension system of claim 9, wherein the connecterfurther comprises an end cap coupled to the inner race and a sealdisposed between the end cap and the inner race.
 11. The suspensionsystem of claim 8, wherein the first swing arm further comprises aflange extending radially outward from an outer surface of the firstmounting member configured to interface with the outer support memberand limit axial movement of the first swing arm.
 12. The suspensionsystem of claim 11, wherein the connecter further comprises a thrustbearing disposed between the flange and the inner race.
 13. Thesuspension system of claim 1, further comprising a guard at leastpartially surrounding the sway bar.
 14. A suspension system for avehicle having a frame, comprising: a first interface member; a secondinterface member, wherein the first interface member and the secondinterface member are positioned along a common central axis; a firstbody member coupled to the first interface member and configured torotate about the common central axis; a second body member coupled tothe second interface member and configured to rotate about the commoncentral axis; and a torsion spring coupled to the first interface memberwith a first splined connection and coupled to the second interfacemember with a second splined connection different than the first splinedconnection, wherein the torsion spring is disposed along the commoncentral axis.
 15. The suspension system of claim 14, wherein the torsionspring comprises a circular bar.
 16. (canceled)
 17. The suspensionsystem of claim 14, wherein the first splined connection includes a maleand female spline having a first diameter and the second splinedconnection includes a male and female spline having a second diameterthat is greater than the first diameter.
 18. The suspension system ofclaim 14, wherein the first splined connection includes a first numberof teeth and the second splined connection includes a second number ofteeth.
 19. The suspension system of claim 14, further comprising an endcap coupled to the first interface member and torsion spring to limitrelative rotation between the torsion spring and the first interfacemember.
 20. The suspension system of claim 19, wherein the end capincludes a locking plug having an internal void that engages the torsionspring and an external periphery that engages the first interfacemember.
 21. An axle assembly for a heavy duty truck, comprising: a firstwheel hub and a second wheel hub; a first drive axle coupled to thefirst wheel hub and a second drive axle coupled to the second wheel hub;a differential assembly coupled to the first drive axle and the seconddrive axle; a first swing arm including a first elongated portion and afirst mounting member having a central axis and coupled to an end of thefirst elongated portion; a second swing arm including a second elongatedportion and a second mounting member having a central axis and coupledto the second elongated portion, wherein the second mounting member iscoaxially aligned with the first mounting member to define an axis ofrotation for the first swing arm and the second swing arm; wherein thefirst wheel hub is coupled to an end of the first elongated portion andthe second wheel hub is coupled to an end of the second elongatedportion; a connecter configured to receive at least one of the firstmounting member and the second mounting member; and a sway bar having acentral axis, wherein the sway bar is coupled to the first swing armwith a first splined connection and coupled to the second swing arm witha second splined connection different than the first splined connection,wherein the sway bar is positioned such that the central axis of thesway bar is coaxially aligned with the axis of rotation.